Bit of a rant coming on here, and I'll start by saying that I've recently been talking to a really good architect who definitely does understand, and fervently believe in, passive house design and construction, and who is very enthusiastic about learning about new methods of construction.

However, I've just sat through 30 minutes of "Building your dream home" (recorded a week or so ago) with a prime example of a pretentious and clearly ignorant architect who had just designed a £350k mobile home that met Passivhaus certification standards. Her level of ignorance regarding the physics of passive house design and construction, and her completely false statements about there being a substantial cost premium associated with meeting such a performance standard were simply beyond belief. For example, she stated that MVHR used recycling and mixing extracted air with incoming fresh air for heat recovery. She also mentioned the need for lots of South facing glazing for summer solar gain (which is plainly completely idiotic - the house will be like a bloody greenhouse!). She went on to say it could be heated in winter by, quote, "one person and a candle" which is total rubbish. She also showed a massive array of completely redundant high tech wizardry, and stated that this "essential" stuff added a lot of cost, but that this would be recovered as energy costs continued to increase. The reality is that it costs no more (in our case around 10% less) to build a passive house than a conventional house.

I appreciate that this programme seems to be a sales pitch for architects, and if they are competent and do a good job (as some in the series have) then all is well and good. However, when they choose to feature architects who clearly don't have a bloody clue when it comes to design, construction or costs of passive houses, yet profess to be "experts", then I'm afraid it makes my blood boil.

The good news is that, out of the eleven architects who have now visited our build, two have got what it takes to get to grips with the melding of science, art, technology and design that has to happen for a good low, or zero, energy house design. We need architects, as they can definitely add great value to the design and detail of a house. However, it seems to me that the profession is way, way behind the curve when it comes to low/zero energy design and the need for working closely with the engineering and technology disciplines that are an essential part of any house of this type.

This is the episode that got me thinking about pre-fab housing and how it could and perhaps should be a more mainstream method of construction given the benefits of construction in a controlled environment. I was however staggered at both the cost of this particular build, and some of the comments she made. The misleading explanation of how MVHR works, was the crowning glory for me.

I too have also had a 'specialist' tell me that I would be able to recover increased building costs through future energy savings on the same kind of scale. When we built our current house, I had a quote back from a builder who was at that time constructing passive type houses (it has to be said for reasonable prices) on the west coast of Scotland. He came to me with his samples of construction materials, and produced a graph showing a near 15% year on year increase in energy/fuel costs to justify what he said would be slightly higher construction costs. At the time it seemed to be accepted that to improve insulation levels to the kind of passive house area would see a 5% uplift in costs, although quite clearly, and as Jeremy has shown, this need not be the case. The fact that his quote was fully double that of my final build saw me swiftly go my own way! One wonders in the case above, how much of the tech / bling was architect or client specified?

I think there are a couple of big issues facing architects trying to move towards working on passive houses.

The first one is cultural, as there is a need for the cold physics and engineering required for an effective low energy house to have a very high priority in the design, and this places some tight bounds on what can and cannot then be done. I get the feeling that some architects aren't used to working within this level of constraint and having to accept that engineering and technological input is as important, or even more important, than design input. Those who already work in heavily restricted areas (such as listed building work etc) are probably more able to adapt, as passive house restraints aren't much different in terms or the control they exert over the design.

The second issue is acquiring good technical knowledge and understanding the basic of some of the systems, like MVHR. There are an awful lot of snake oil sales people in the renewables/low energy housing products market, and it is far too easy for someone who lacks technical knowledge to be hoodwinked into thinking that they need a lot of high tech stuff to build a house like this.

Some clients are just going to assume that their architect is an expert and so trust them implicitly, which may well just add to the problem.

Out of interest how have you worked out that yours has cost 10% less to build to build to passive standard? Is it comparing your cost to an equivalent building regs one? Does it take your time into account and other cost saving things? Surely the extra insulation and triple glazing, airtight detailing etc needed lifts costs rather than reduces? Where is the cost saving made? Obviously long term fuel costs will be saved, is this taken into account?

Out of interest how have you worked out that yours has cost 10% less to build to build to passive standard? Is it comparing your cost to an equivalent building regs one? Does it take your time into account and other cost saving things? Surely the extra insulation and triple glazing, airtight detailing etc needed lifts costs rather than reduces? Where is the cost saving made? Obviously long term fuel costs will be saved, is this taken into account?

I had quotes from several companies for the build, and these varied from only offering just better than building regs performance (despite my specific request that they quote for the sort of U values I was looking for) to true passive house levels of airtightness and insulation. Only one company I asked to quote would actually guarantee airtightness to PH standards, although since then there are a couple of others I've heard of that will. So, this gave me a pretty good feel for the sort of cost of a conventional house. My feelings were confirmed by one of the architects who visited and who was specifically focussed on the build costs, and the cost breakdown of various elements. He was the one who told me that my basic build (the foundations, insulated and airtight frame, with PH certified glazing and doors) had come in at around 10% less than the cost of a standard one-off house of the same size in this area. His 10% less figure is substantially smaller than the spread of quotes I received - the most expensive quote was more than 30% over what I paid, for a build with thermal performance that wasn't much better than building regs require.

Certainly there are areas outside the basic airtight and insulated weather tight house where my own work has reduced fitting out costs, but the comparison was just about the house construction cost, not the added extras, like oak doors, stairs, kitchen, stone flooring etc. The areas where my own efforts have saved money have been in being the designer and project manager (so saving architects/project managers fees) and in doing some of the fitting out internally (like fitting the ventilation and heating system, doing all the plumbing, fitting the kitchen, bathroom suites, utility room, WCs etc).

Triple glazing costs little, or no, more than double glazing now. We paid £340 per m² for PH certified doors and windows, including fitting, which isn't that expensive. Similarly airtightness detailing in our build is by design, and adds perhaps 1 man day of extra effort, if that, so is in the noise in terms of cost.

I cant help but think that if you had built your house as you did (project manage design, detailing etc) but only to building regs it would have been much cheaper. Triple glazing was more expensive everywhere I looked (I asked a lot of companies for both prices) yet I keep seeing on this and other forums that it is much of a muchness. My slab is the same passive one as your own, yet I had the option of removing 1 or 100mm of the insulation off which would still have me well above regs yet save me some hundreds in materials. Same with extra insulation needed in walls and roof. The airtight tape is some hundreds of pounds plus £100s extra in applying diligently as is the compriband tape and extra materials to get airtight. The MVHR is some thousands extra as were passive alternatives compared to vents over each window.

Comfort and energy saving in future these houses are and I want everyone to pursue this route, but I just cant see how they are cheaper to build or remotely similar.

All I can say is that my total build costs, excluding the land cost and the cost of getting the land level (which was compensated for by getting the land at much less than the market rate here for the area, because of the known high cost of getting it level and getting water to it) have come to around £1300/m², which, for the spec we've got seems pretty good. I couldn't find a local builder who could come close to the cost we've ended up paying, and the relatively local architect who looked at my detailed costs said the same. Around here the majority of self-builds seem to be around the £1400/m² mark, and I've only seen one that is close to ours in performance (but have a feeling that cost over £1500/m²).

As I said before, if you design in airtightness then there is no need to uses masses of expensive tape, membranes, labour etc to get the house airtight. Our house is very airtight by design, without using anything in the way of fancy materials to make it so. It also uses pretty cheap insulation, EPS for the floor slab (which is a lot cheaper than some of the alternatives) and Warmcell for the walls and roof fill (again cheaper, and vastly less labour to fit - around 1 days work to insulate all the walls and the roof) The total cost of the foundations, all insulation and house frame, with roof battened and membrane covered and guaranteed PH or better airtightness came to £408/m². Had we not had vaulted ceilings, but opted for roof trusses, then this cost would have been reduced by around £30/m².

They key to getting the price down is cutting down the labour time involved and using cost effective materials, with clever design to get the required insulation and airtightness level. If you tried to build a conventional construction house to the same thermal standard as we have then yes, the cost would be 10 to 15% more, because of the additional material and labour cost, but it doesn't have to be like that.

I could have fitted a standard, off-the-shelf, MVHR for around £800 and it would still have done the job of recovering waste heat and keeping the energy consumption down (in fact it would have resulted in a lower energy consumption). This isn't that much more expensive than the mandatory ventilation that would have to be fitted to a conventional house (like kitchen, bathroom, WC extracts, for example). Similarly, had I been on the gas grid I'd have fitted a small combi boiler rather than a heat pump, but the cost would have been around the same (We had our combi replaced 4 or 5 years ago and the cost was around £2k, the ASHP in the new build cost £1750)..

I appreciate the sentiment regarding many architects but not the assertion or the evidence presented that a passive house costs less to build than a standard house. Standard double glazed windows and doors would be less than £100/m2 fitted, so the 3g PH ones might add £5k for a small house. MVHR, like a Vent Axia Sentinel Plus, fitted adds another £3k over the cost of extractors and needs room to house. Airtightness and additional insulation also does not come free, although I appreciate that thoughtful design make it far cheaper than otherwise.

Your project management skills and your other extensive hands-on work replacing some high cost trades no doubt contributed to reduced cost, but I am sure you could have applied this to a non-passive house build and finished with an even lower cost build.

Don't forget that there is no requirement for expensive heating systems for a PH, and I fail to see why figures of "thousands of pounds" keep being quoted for MVHR. The Ventaxia unit is pretty good, but retails for less than £1k (I found it on sale last year when I was looking around for around £800) and there are cheaper (but admittedly less efficient) units around for around £500. As mentioned above, even a non-PH needs extract ventilation in some rooms, and these are going to cost a couple of hundred pounds or more, so there is only a modest increase over the cost of extract-only ventilation.

I can take a rough stab at how much my own work has contributed to the build, probably around £25k to £30k at a guess, so without my DIY efforts the build would have come out at around £1500/m². However, we opted to spend an extra £3k on an active MVHR with heating and cooling, we spent nearly double our original budget on the kitchen (roughly £9k more than planned) and also spent more than twice as much as planned on oak internal joinery (including a solid oak staircase, with plate glass balustrade), which added around another £5k to the build costs (over just using off-the-shelf stairs, softwood doors, skirtings, architrave etc). So, in real terms part of my own efforts allowed us to spend around £17k over the original budget; had we not opted to do this, and had we used a project manager and no DIY from me, then we'd have come in at around £1400/m². £1400/m² is about 7% less than I could have had the same size house built locally from block and brick, and I would never have been allowed by the planners to build it like that anyway (they were insistent that it either be clad in local stone or timber, and I wouldn't have been allowed things like uPVC windows). None of the timber frame/SIPs companies I got quotes from came in under £1500/m², either, most were closer to £1600/m² in fact (and one was around £1650/m²).

Admittedly some of that is down to being in an area where labour costs are relatively high, plus being within an AONB and opposite a grade II listed building (so subject to the same sort of external materials and appearance restrictions), but even the basic timber frame/SIPs frame prices I was getting from suppliers were way more than I was expecting, even for a relatively standard building regs type insulation level. For example, the nearest timber frame supplier to me quoted over £65k just for the house frame (erected), without the £10k or so I'd have had to add for the foundations. Factor in that this was for wall U values of 0.18 and a roof U value of 0.19, and that it would have cost an extra £5k or £6k to get them even close to the sort of insulation level I was looking for. Even for this sort of thermal performance their erected insulated frame and foundation cost was going to come to around £75k, whereas our PH level house frame and foundations came to around £53k erected, a pretty massive difference.

I'm sure that if you live in an area where labour costs are lower, and you don't have planning restrictions that definitely favoured our chosen build method, then you could pay a premium for PH type levels of performance. I'm still not convinced that there is a significant cost premium, though, unless you go out of your way to choose very expensive suppliers.

At the end of that program I was waiting on a message to the effect
" this program was a party political broadcast sponsored by every architect in the land."
In terms of cost my triple glazed windows cost £900 dearer than the best A rated double glazing I got a price for. No brainer for me. Worked out an extra £60 for each opening.
For the airtightness tape and membrane I got enough material for my build for £700. It is by gerband a German company and is the most sticky tape I have ever touched.
There are still gd deals to be found it is whether you are prepared to put the time in finding them.

I put the sential plus system in mine. Again the deal was right. All in with 100m of airflex duct 40m of insulated flexy duct all the manifolds,5 ceiling covers and the rest of the bits you need for it for £1500.
With me its all about the deal were now my wife generally walks away when we get to that stage as I haggle over a few quid.

At the end of that program I was waiting on a message to the effect
" this program was a party political broadcast sponsored by every architect in the land."

Me too. The programme does seem to have a focus on advertising the benefits architects bring, but then shoots itself in the foot when you look at the massive cost implications of some of the architect-driven ideas.

A mobile home can't be bigger externally than 20m x 6.7m and if it has PH standard insulation that really means the internal floor area can't exceed about 115 to 120m², in all probability the net internal floor area will be less than this. So, even being optimistic with the floor area that thing cost around £3,000 per m², which is a staggeringly high build cost, even for a permanent house.

I know what you mean about putting the hours in, the frustrating thing for me is that it takes me three times as long to do a proper job as it would take a skilled tradesman, especially with things that I'm having to learn on the job (and so end up doing twice..........). I'm putting around 50 hours a week in, and am trying hard to stick to only being on site Monday to Friday, with weekends off. The snag is that my 50 hours a week is probably only a day and half to two days work for someone who does this stuff for a living.

I am the same, it does take me a bit longer but the jobs i can do i do as best i can. Never plasterboarded before but now with the wife's help we are "pros". Well nearly there. She makes sure i do it right. I have been all over anybody who has done any work making sure no short cuts are being used so when i do something myself i take my time and do it right as some jobs you only get one shot at. I am at mine ever day i am off work esp weekends so am doing my own work then working at the site with little or no time of but the child starts her new school beside my site in September so have a deadline to work to. Plasterers are in next Monday so i have to get it boarded or they will start another house and i will have no chance of being in for September.

My plot was free it was my parents front garden. Site beside it went for £30,000 so not that dear for a site in NI. The groundworks i will do myself as i have my digger ticket so only need a bit of help for fitting the pipes. My services bill is around £2500 for electric, water and BT. Water was the most expensive as there is a road crossing but it was just under £1700. Electric pole on site as well as bt thats why they are cheap. I have to lay the ducts for both.

Out of interest which channel was this "building your dream home" programme on?

Either I just plain missed it, or it was on a pay tv channel (I don't "do" pay tv)

"Dream" is the new homeshow buzzword.

"Building the Dream" is on C4 by "Architectural Designer" Charlie Luxton which tell the story of a couple of houses per episode. The USP is Charlie suggesting a couple of improvements and showing how good they were. Still running,http://www.channel4....lding-the-dream

"Building Dream Homes" is on the Beeb, which covers houses over a series of episodes, with the lens partly on the vicissitudes/psychological damage of life as a self-builder, while the house is built. Currently not running. 2 days left on iPlayer for last episode.http://www.bbc.co.uk...rammes/b0467j0x

I think I've also seen one involving Laurence Llewellyn Bowen, but I switched it off too quickly to find out more in case some rogue purple ruched curtainettes appeared.

Currently my favourite is George Clarke's Amazing Spaces about what can be done in tiny spaces. Totally whacky but a high density of great ideas. The latest I liked was a toddler's sand pit underneath the step down from a patio - double bubble and it keeps it dry.http://www.channel4....-amazing-spaces